STATISTICAL ANALYSIS FOR MANAGERS
only 16 questions
1. For some positive value of Z, the probability that a standard normal variable is between 0 and Z is 0.3770. The value of Z is:
a. 0.18
b. 0.81
c. 1.16
d. 1.47
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2. If we know that the length of time it takes a college student to find a parking spot on central campus follows a normal distribution with a mean of 3.5 minutes and a standard deviation of 1 minute, find the probability that a randomly selected college student will find a parking spot in less than 3 minutes.
a. 0.3551
b. 0.3085
c. 0.2674
d. 0.1915
3. Given the data above, find the probability that a randomly selected college student will take between 2 and 4.5 minutes to find a parking spot.
a. 0.0919
b. 0.2255
c. 0.4938
d. 0.7745
4. Given the data above, find the point in the distribution that 75.8% of the college students exceed when trying to find a parking spot.
a. 2.8 minutes.
b. 3.2 minutes.
c. 3.4 minutes.
d. 4.2 minutes.
5. The owner of a fish market determined that the average weight for a catfish is 3.2 pounds with a standard deviation of 0.8 pound. A citation catfish should be one of the top 2% in weight. Assuming the weights of catfish are normally distributed, at what weight ( in pounds ) should the citation designation be established?
a. 1.56 pounds.
b. 4.84 pounds.
c. 5.20 pounds.
d. 7.36 pounds.
6. Suppose a sample of n = 50 items is drawn from a population of manufactured products and the weight, X, of each item is recorded. Prior experience has shown that the weight has a probability distribution with µ = 6 ounces and s = 2.5 ounces. Which of the following is true about the sampling distribution of the sample mean if a sample of size “15” is selected?
a. the mean of the sampling distribution is 6 ounces.
b. the standard deviation of the sampling distribution is 2.5 ounces.
c. the shape of the sample distribution is approximately normal.
d. all of the above are correct.
7. At a computer manufacturing company, the actual size of computer chips is normally distributed with a mean of 1 centimeter and a standard deviation of 0.1 centimeter. A random sample of 12 computer chips is taken. What is the standard error for the sample mean?
a. 0.029
b. 0.050
c. 0.091
d. 0.120
8. The owner of a fish market has an assistant who has determined that the weights of catfish are normally distributed, with mean of 3.2 pounds and standard deviation of 0.8 pound. If a sample of 64 fish yields a mean of 3.4 pounds, what is the probability of obtaining a sample mean this large or larger?
a. 0.0001
b. 0.0013
c. 0.0228
d. 0.4987
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9. The standard error of the mean for a sample of 100 is 30. In order to cut the standard error of the mean to “15”, we would:
a. increase the sample size to 200.
b. increase the sample size to 400.
c. decrease the sample size to 50.
d. decrease the sample size to 25.
44. The amount of bleach that a machine pours into bottles has a mean
of 36 ounces with a standard deviation of 0.15 ounces. Suppose we
take a random sample of 36 bottles filled by this machine.
The probability that the mean of the sample is between 35.94 and
36.06 ounces is 0.9836 .
TRUE FALSE
Problems ( Fill In The Blank )
The amount of time necessary for assembly line workers to complete a product is a normal random variable with a mean of fifteen ( 15 ) minutes and a standard deviation of two ( 2 ) minutes.
Requirement:
1) What is the probability that a product is assembled in less than 12 minutes?
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2) What is the probability that a product is assembled between 14 and 16 minutes?
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3) What is the probability that a product is assembled between 10 and 12 minutes?
______________
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4) What is the probability that a product is assembled in more than 11 minutes?
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5) What is the probability that a product is assembled in less than 20 minutes?
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6) Within how many minutes would 70% of the products be assembled?
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